Openstack client for creating and destroying instances

openstack_api.py

"""Openstack client API for creating and destroying instances with the Nova API

Date: 04/09/2019
Author: Enrique Carpintero
"""

import requests
import json

class OpenStackAPI:
    def __init__(self, api_host):
        self.host = api_host

    def authenticate(self, user_id, password, project_id):
        """Authenticates with the password method on Keystone
        and saves the token on the object for later use.
        """

        r = requests.post("{}:5000/v3/auth/tokens".format(self.host), json= {
            "auth": {
                "identity": {
                    "methods": [
                        "password"
                    ],
                    "password": {
                        "user": {
                            "id": user_id,
                            "password": password
                        }
                    }
                },
                "scope": {
                    "project": {
                        "id": project_id
                    }
                }
            }
        })


        # 
        try:
            self.headers = {
                'X-Auth-Token': r.headers['X-Subject-Token'],
                'Content-Type': 'application/json'
            }
        except KeyError:
            print("Could not get token from Keystone")
            raise SystemExit

    def get_instances(self):
        """Returns a list of all available instances
        
        Reference: https://docs.openstack.org/api-ref/compute/?expanded=show-server-details-detail#list-servers
        """
        r = requests.get("{}:8774/v2.1/servers".format(self.host), headers=self.headers)

        return r.json()

    def get_instance_data_by_id(self, instance_id):
        """Returns instance data provided by Openstack
        
        Reference: https://docs.openstack.org/api-ref/compute/?expanded=show-server-details-detail#show-server-details
        """
        r = requests.get("{}:8774/v2.1/servers/{}".format(self.host, instance_id), headers=self.headers)

        return r.json()

    def get_instance_ip(self, instance_id):
        """Return the instance IP as a string. Returns False after 100 failed attempts.

        Hammers the API on a loop until Neutron (network) allocates an IP.
        """

        for _ in range(100):
            try:
                instance = self.get_instance_data_by_id(instance_id)
                return instance['server']['addresses']['sharednet1'][0]['addr']
            except KeyError:
                continue

            return False

    def create_instance(self, instance_name, image_id, flavor_id, network_id, security_group_name = None, user_data = None):
        """Nova API reference: https://docs.openstack.org/api-ref/compute/?expanded=create-server-detail#create-server

        image_id, flavor_id and network_id can be obtained through Horizon
        config_drive should always be True
        user_data is a base64 encoded string for the cloud-init
        """
        payload = {
            "server": {
                "name": instance_name,
                "imageRef": image_id,
                "flavorRef": flavor_id,
                "networks": [{
                    "uuid": network_id
                }],
                "config_drive": True
            }
        }

        if security_group_name is not None:
            payload['server']['security_groups'] = [{ "name": security_group_name }]

        if user_data is not None:
            payload['server']['user_data'] = user_data

        r = requests.post("{}:8774/v2.1/servers".format(self.host), headers=self.headers, json= payload)

        # Status code for resource creation is 202 Accepted
        if r.status_code is not 202:
            print("Could not create Nova instance", r.json())
        
        return r.json()

    def delete_instance_by_id(self, instance_id):
        """Returns True if instance deletion is successful. False if unsuccessful
        """

        r = requests.delete("{}:8774/v2.1/servers/{}".format(self.host, instance_id), headers=self.headers)

        # 204 No Content - request was successful
        return True if r.status_code is 204 else False

    def delete_all_instances(self):
        """Iterates over created instances and executes a delete for each one of them

        Once that is completed it checks if all instances were in fact deleted. 
        """

        instances = self.get_instances()

        for instance in instances['servers']:
            if self.delete_instance_by_id(instance['id']) is not True:
                print("Could not delete instance with name: {}".format(instance['name']))

        instances = self.get_instances()

        return True
            ```